Heart failure (HF) is a worldwide epidemic that contributes considerably to the overall cost of health care in developed nations. The number of people afflicted with this complex disease is increasing at an alarming pace-a trend that is likely to continue for many years to come. The overall goal of our proposed research is to optimize a therapy for HF that involves percutaneous injection of a hydrogel (Algisyl-LVR) in the failing myocardium. Given the cardiovascular system's complexity, a multi-disciplinary expertise across experimental and computational domains is required to fully investigate this novel HF therapy. The three specific aims include the following: First, we will validate mathematical (finite element models of failing left ventricles that have been treated with Algisyl-LVR + coronary artery bypass grafting or Algisyl-LVR alone. The finite element models will have realistic 3D geometries based on magnetic resonance imaging and validated with in-vivo myocardial strain versus left and right ventricular pressure measurements. Additionally, ex-vivo 3D myofiber orientation and direct force measurements in skinned fiber preparations will be made. Second, we will use the validated finite element models and our method for automatically optimizing medical devices for treating HF to design the optimal Algisyl-LVR injection pattern and test it in swine with systolic HF. Lastly, we will deliver Algisyl-LVR percutaneously, using the optimal injection pattern determined in Aim 2, and test it in swine with systolic HF. The proposed approach and methodologies are innovative in simulation of animal-specific device therapy that holds very significant promise for treatment of the epidemic of HF.